Played last night into early morning, the epic almost six-hour, five-set Men's Singles Final of the 2012 Australian Open between top two seeds Novak Djokovic and Raphael Nadal will be long-remembered by tennis purists for many reasons.
For economists, however, one relatively minor incident may just stand out, if for nothing else as a game-theoretic oddity: Nadal challenged the call on his own serve [watch footage], which had been ruled in by the line judge (and not overruled by the chair umpire), ostensibly because Djokovic rifled a rapid-fire winner in return, at a not-so-critical moment in the second set...and it almost worked to earn a replay of the point for him, as Hawkeye ruled the serve to be in only by a hair's breath.
Of amusement is how neither of the host broadcaster commentators Lleyton Hewitt nor Jim Courier (both former world number ones) appeared to know whether this was indeed permissible under the current rules of the Challenge System, especially since the former is still a tour professional (he had bowed out in four sets to Djokovic in the fourth round). Fortunately, the chair umpire knew better, although Djokovic protested briefly on the basis that it took Nadal too long to indicate the intention to challenge, however, given the (weak in one's opinion) standards of enforcement of time limits to indicate, the chair umpire was probably correct in allowing it.
Perhaps it worth wondering whether ITF officials and collaborators foresaw this (and other hitherto unobserved unusual scenarios) when drafting the specifics of the system, and indeed whether in light of this occurrence they will decide to 'close the loophole', though I'd doubt it, since there seems to be nothing fundamentally wrong with this type of challenge in principle.
Since less than half of all challenges currently are upheld, if there is a reform worth considering, it would be the limiting of challenges to two (incorrect) per set, as originally in the 2007 Australian Open, to reduce the number of more frivolous and tactical challenges, which appear to have been rising in incidence more recently as players have become more used to - and more able to exploit - the system.